Conventionally, workpieces are conveyed in the process of manufacturing, for example, various plate-shaped products. Particularly in the case of processing a workpiece while the workpiece is being conveyed, it is necessary that the workpiece (hereinafter, “conveyed workpiece”) be in a proper orientation while being conveyed.
Examples of such a conveyed workpiece include a substrate of a thin silicon solar cell and a substrate of a CIGS solar cell. (These types of solar cells are collectively referred to as “thin-film solar cells” in the description and claims herein.) Such a substrate is formed in the following manner: forming a metal film or a semiconducting material film such as a silicon film on one surface of a glass substrate (i.e., deposition or film formation), thereby forming a thin-film layer (having a thickness of, for example, several hundred nm to several tens of μm) on the one surface of the glass substrate. Hereinafter, a description is given by taking a thin-film solar cell substrate as one example of the conveyed workpiece.
For example, as shown in FIGS. 12A to 12G, a process of manufacturing a thin-film solar cell substrate includes forming, on the upper surface of a glass substrate 100 (FIG. 12A), a transparent electrode layer 101 (FIG. 12B), and performing patterning on the transparent electrode layer 101 by irradiating the transparent electrode layer 101 with a laser beam 108 emitted from a laser machining device, thereby forming machining lines 102 in the transparent electrode layer 101 (FIG. 12C). The conveyed workpiece 107, including the transparent electrode layer 101 in which the machining lines 102 have been formed, is further processed such that a photoelectric conversion layer 103 is formed on the upper surface of the transparent electrode layer 101 (FIG. 12D), and photoelectric conversion layer machining lines 104 are formed in the photoelectric conversion layer 103 by a laser machining device (FIG. 12E). Thereafter, the conveyed workpiece 107, including the photoelectric conversion layer 103 in which the machining lines 104 have been formed, is further processed such that a back surface electrode layer 105 is formed on the upper surface of the photoelectric conversion layer 103 (FIG. 12F). Then, back surface electrode layer machining lines 106 are formed in the back surface electrode layer 105 by a laser machining device (FIG. 12G). The substrate 100, on which the pattering has been thus performed, is completed as a solar cell module.
As described above, in the case of a thin-film solar cell, film forming is performed on the surface of the conveyed workpiece (substrate 100) a plurality of times, and precise patterning needs to be performed on each of the formed thin-film layers. The required precision is, for example, error control in units of micrometers. Therefore, a laser machining device capable of precisely conveying a conveyed workpiece and precisely irradiating a thin-film layer of the conveyed workpiece with a laser beam is required.
One example of such a laser machining device is a laser machining device for which the applicant of the present application previously filed a patent application. As shown in FIG. 13, a laser machining device 110 is configured to hold and feed a conveyed workpiece 107 in a workpiece feeding direction X with a constant-speed feeder 111, and while feeding the conveyed workpiece 107, irradiate the conveyed workpiece 107 with a laser beam 108, which is emitted from a beam scanning unit 109 and scanned in a scanning direction Y, thereby performing patterning on the conveyed workpiece 107. The constant-speed feeder 111 includes a rotating shaft (θ axis) rotatable in a planar direction so that yawing and the like of the conveyed workpiece 107 can be corrected. Moreover, the laser machining device 110 includes a camera 113 configured to detect a machining reference position (e.g., an end face) of the conveyed workpiece 107.
Further, as shown in FIG. 14, while feeding the conveyed workpiece 107 in the workpiece feeding direction X, the laser machining device 110 emits a single laser beam 108 and scans the single laser beam 108 in the scanning direction Y, which crosses the workpiece feeding direction X, at a high speed (e.g., several times faster than a conventional speed). In this manner, patterning of forming straight machining lines 112 on the conveyed workpiece 107 perpendicularly to the feeding direction X can be performed.
As one example of this kind of conventional art, there is a substrate processing apparatus configured to perform a process while moving a glass substrate or the like and a substrate processor relative to each other, the substrate processor being configured to perform a predetermined process on the substrate. The substrate processing apparatus is configured to: measure an error that occurs during scanning of the substrate, such as yawing, in a first direction and a second direction perpendicular to the first direction; correct the error in the first direction by a corrector configured to control the conveyance of the substrate; and correct the error in the second direction by the substrate processor based on a measured distance. By performing the correction, the substrate processing apparatus can precisely perform the process at a predetermined position on the substrate (see Patent Literature 1, for example).
Another example of the conventional art is a panel substrate manufacturing method, in which a display panel substrate of a liquid crystal display or the like is irradiated with a light beam, and thereby a pattern is drawn on the substrate. The method includes: detecting a running error of a stage, the stage being configured to hold the substrate and run together with the substrate; correcting coordinates of drawing data based on results of the detection; and feeding the corrected drawing data to a drive circuit of a light beam emitting device (see Patent Literature 2, for example).